Dubbo整合Seata实现AT模式分布式事务

其他 2020-08-12 10:28:38 阅读次数: 0

Seata

Seata 是一款开源的分布式事务解决方案，致力于提供高性能和简单易用的分布式事务服务。Seata 将为用户提供了 AT、TCC、SAGA 和 XA 事务模式，为用户打造一站式的分布式解决方案。

Seata的事务模式
Seata针对不同的业务场景提供了四种不同的事务模式，具体如下

  • AT模式： AT 模式的一阶段、二阶段提交和回滚（借助undo_log表来实现）均由 Seata 框架自动生成，用户只需编写“业务SQL”，便能轻松接入分布式事务，AT 模式是一种对业务无任何侵入的分布式事务解决方案。
  • TTC模式： 相对于 AT 模式，TCC 模式对业务代码有一定的侵入性，但是 TCC 模式无 AT 模式的全局行锁，TCC 性能会比 AT模式高很多。（ 适用于核心系统等对性能有很高要求的场景。）
  • SAGA模式：Sage 是长事务解决方案，事务驱动，使用那种存在流程审核的业务场景，如： 金融行业，需要层层审核。
  • XA模式： XA模式是分布式强一致性的解决方案，但性能低而使用较少。

AT模式

AT模式，分为两个阶段

  • 一阶段：业务数据和回滚日志记录在同一个本地事务中提交，释放本地锁和连接资源
  • 二阶段：提交异步化 （ 或者事务执行失败，回滚通过一阶段的回滚日志进行反向补偿）

一阶段:本地事务提交

在一阶段，Seata 会拦截“业务 SQL”，首先解析 SQL 语义，找到“业务 SQL”要更新的业务数据，在业务数据被更新前，将其保存成“before image”，然后执行“业务 SQL”更新业务数据，在业务数据更新之后，再将其保存成“after image”，最后生成行锁。以上操作全部在一个数据库事务内完成，这样保证了一阶段操作的原子性。
在这里插入图片描述

二阶段：执行成功，进行分布式事务提交

业务 SQL”在一阶段已经提交至数据库， 所以 Seata 框架只需将一阶段保存的快照数据和行锁删掉，完成数据清理即可。
在这里插入图片描述
二阶段：执行失败，进行业务回滚
首先对比“数据库当前业务数据”和 “after image”，避免发生业务脏写（类似于CAS操作），完成校验后用“before image”还原业务数据，并且删除中间数据。
在这里插入图片描述

Seata Server安装

第一步：下载安装服务端,并解压到指定位置

unzip  seata-server-1.1.0.zip

seata的目录结构：

  • bin:存放各系统的启动脚本
  • conf:存放seata server启动时所需要配置信息、数据库模式下所需要的建表语句
  • lib:运行seata server所需要的的依赖包

第二步：配置seata
seata的配置文件（conf目录下）

  • file.conf: 该文件用于配置存储方式、透传事务信息的NIO等信息，默认对应registry.conf中file配置方式
  • registry.conf:seata server核心配置文件，可以通过该文件配置服务注册方式、配置读取方式。

注册方式目前支持file、nacos、eureka、redis、zk、consul、etcd3、sofa等方式，默认为file,对应读取file.conf内的注册方式信息。
读取配置信息的方式支持file、nacos、apollo、zk、consul、etcd3等方式，默认为file，对应读取file.conf文件内的配置。

修改registry.conf

  • 注册中心使用Nacos
  • 配置中心使用file进行配置
# 注册中心配置，用于TC,TM,RM的相互服务发现
registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  type = "nacos"
  consul {
    cluster = "seata"
    serverAddr = "127.0.0.1:8848"
  }
}
# 配置中心配置，用于读取TC的相关配置
config {
  # file、nacos 、apollo、zk、consul、etcd3
  type = "file"
  file {
    name = "file.conf"
  }
}

修改file.conf，配置中心配置，用于读取TC的相关配置

store {
  ## store mode: file?.b
  mode = "file"

  ## file store property
  file {
    ## store location dir
    dir = "sessionStore"
    # branch session size , if exceeded first try compress lockkey, still exceeded throws exceptions
    maxBranchSessionSize = 16384
    # globe session size , if exceeded throws exceptions
    maxGlobalSessionSize = 512
    # file buffer size , if exceeded allocate new buffer
    fileWriteBufferCacheSize = 16384
    # when recover batch read size
    sessionReloadReadSize = 100
    # async, sync
    flushDiskMode = async
  }


  ## database store property
  db {
    ## the implement of javax.sql.DataSource, such as DruidDataSource(druid)/BasicDataSource(dbcp) etc.
    datasource = "dbcp"
    ## mysql/oracle/h2/oceanbase etc.
    dbType = "mysql"
    driverClassName = "com.mysql.jdbc.Driver"
    url = "jdbc:mysql://127.0.0.1:3306/seata"
    registry.confuser = "mysql"
    password = "mysql"
    minConn = 1
    maxConn = 10
    globalTable = "global_table"
    branchTable = "branch_table"
    lockTable = "lock_table"
    queryLimit = 100
  }
}

第三步：创建seata数据库、以及所需的三张表

  • global_table: 存储全局事务session数据的表
  • branch_table:存储分支事务session数据的表
  • lockTable:存储分布式锁数据的表
-- -------------------------------- The script used when storeMode is 'db' --------------------------------
-- the table to store GlobalSession data
CREATE TABLE IF NOT EXISTS `global_table`
(
    `xid`                       VARCHAR(128) NOT NULL,
    `transaction_id`            BIGINT,
    `status`                    TINYINT      NOT NULL,
    `application_id`            VARCHAR(32),
    `transaction_service_group` VARCHAR(32),
    `transaction_name`          VARCHAR(128),
    `timeout`                   INT,
    `begin_time`                BIGINT,
    `application_data`          VARCHAR(2000),
    `gmt_create`                DATETIME,
    `gmt_modified`              DATETIME,
    PRIMARY KEY (`xid`),
    KEY `idx_gmt_modified_status` (`gmt_modified`, `status`),
    KEY `idx_transaction_id` (`transaction_id`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8;
-- the table to store BranchSession data
CREATE TABLE IF NOT EXISTS `branch_table`
(
    `branch_id`         BIGINT       NOT NULL,
    `xid`               VARCHAR(128) NOT NULL,
    `transaction_id`    BIGINT,
    `resource_group_id` VARCHAR(32),
    `resource_id`       VARCHAR(256),
    `branch_type`       VARCHAR(8),
    `status`            TINYINT,
    `client_id`         VARCHAR(64),
    `application_data`  VARCHAR(2000),
    `gmt_create`        DATETIME,
    `gmt_modified`      DATETIME,
    PRIMARY KEY (`branch_id`),
    KEY `idx_xid` (`xid`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8;
-- the table to store lock data
CREATE TABLE IF NOT EXISTS `lock_table`
(
    `row_key`        VARCHAR(128) NOT NULL,
    `xid`            VARCHAR(96),
    `transaction_id` BIGINT,
    `branch_id`      BIGINT       NOT NULL,
    `resource_id`    VARCHAR(256),
    `table_name`     VARCHAR(32),
    `pk`             VARCHAR(36),
    `gmt_create`     DATETIME,
    `gmt_modified`   DATETIME,
    PRIMARY KEY (`row_key`),
    KEY `idx_branch_id` (`branch_id`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8;

第四步：启动seata server

sh seata-server.sh -p 8091 -h 0.0.0.0 -m file 

Options: 

--host, -h 
The host to bind. 
Default: 0.0.0.0 

--port, -p 
The port to listen. 
Default: 8091 

--storeMode, -m log store mode : file、db 
Default: file 

--help

补充：

  • 外网访问：如果需要外网访问 需要将0.0.0.0转成外网IP
  • 后台启动： nohup sh seata-server.sh -p 8091 -h 127.0.0.1 -m file >catalina.out 2>&1 &

在nacos中看到seata的注册信息
在这里插入图片描述

Dubbo整合Seata实现AT模式

注入依赖

<!--seata-->
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-alibaba-seata</artifactId>
    <version>2.1.0.RELEASE</version>
    <exclusions>
        <exclusion>
            <artifactId>seata-all</artifactId>
            <groupId>io.seata</groupId>
        </exclusion>
    </exclusions>
</dependency>
<dependency>
    <groupId>io.seata</groupId>
    <artifactId>seata-all</artifactId>
    <version>1.1.0</version>
</dependency>

application.properties 配置文件

#mysql
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.driverClassName=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/dubbodemo
spring.datasource.username=mysql
spring.datasource.password=mysql

spring.cloud.alibaba.seata.tx-service-group=springcloud-alibaba-producer-test

resoures目录下新建 file.conf ，配置如下

transport {
  # tcp udt unix-domain-socket
  type = "TCP"
  #NIO NATIVE
  server = "NIO"
  #enable heartbeat
  heartbeat = true
  # the client batch send request enable
  enableClientBatchSendRequest = false
  #thread factory for netty
  threadFactory {
    bossThreadPrefix = "NettyBoss"
    workerThreadPrefix = "NettyServerNIOWorker"
    serverExecutorThreadPrefix = "NettyServerBizHandler"
    shareBossWorker = false
    clientSelectorThreadPrefix = "NettyClientSelector"
    clientSelectorThreadSize = 1
    clientWorkerThreadPrefix = "NettyClientWorkerThread"
    # netty boss thread size,will not be used for UDT
    bossThreadSize = 1
    #auto default pin or 8
    workerThreadSize = "default"
  }
  shutdown {
    # when destroy server, wait seconds
    wait = 3
  }
  serialization = "seata"
  compressor = "none"
}
# service configuration, only used in client side
service {
  #transaction service group mapping
  ### springcloud-alibaba-demo-test 对应的是application.properties中配置的
  ### seata对应 seata-server中配置的集群名称clutser
  vgroupMapping.springcloud-alibaba-producer-test= "seata"
  seata.grouplist = "127.0.0.1:8091"
  #degrade, current not support
  enableDegrade = false
  #disable seata
  disableGlobalTransaction = false
}
#client transaction configuration, only used in client side
client {
  rm {
    asyncCommitBufferLimit = 10000
    lock {
      retryInterval = 10
      retryTimes = 30
      retryPolicyBranchRollbackOnConflict = true
    }
    reportRetryCount = 5
    tableMetaCheckEnable = false
    reportSuccessEnable = false
    sqlParserType = druid
  }
  tm {
    commitRetryCount = 5
    rollbackRetryCount = 5
  }
  undo {
    dataValidation = true
    logSerialization = "jackson"
    logTable = "undo_log"
  }
  log {
    exceptionRate = 100
  }
}


## transaction log store, only used in server side
store {
  ## store mode: file、db
  mode = "file"
  ## file store property
  file {
    ## store location dir
    dir = "sessionStore"
    # branch session size , if exceeded first try compress lockkey, still exceeded throws exceptions
    maxBranchSessionSize = 16384
    # globe session size , if exceeded throws exceptions
    maxGlobalSessionSize = 512
    # file buffer size , if exceeded allocate new buffer
    fileWriteBufferCacheSize = 16384
    # when recover batch read size
    sessionReloadReadSize = 100
    # async, sync
    flushDiskMode = async
  }


  ## database store property
  db {
    ## the implement of javax.sql.DataSource, such as DruidDataSource(druid)/BasicDataSource(dbcp) etc.
    datasource = "dbcp"
    ## mysql/oracle/h2/oceanbase etc.
    dbType = "mysql"
    driverClassName = "com.mysql.jdbc.Driver"
    url = "jdbc:mysql://127.0.0.1:3306/seata"
    user = "mysql"
    password = "mysql"
    minConn = 1
    maxConn = 10
    globalTable = "global_table"
    branchTable = "branch_table"
    lockTable = "lock_table"
    queryLimit = 100
  }
}
## server configuration, only used in server side
server {
  recovery {
    #schedule committing retry period in milliseconds
    committingRetryPeriod = 1000
    #schedule asyn committing retry period in milliseconds
    asynCommittingRetryPeriod = 1000
    #schedule rollbacking retry period in milliseconds
    rollbackingRetryPeriod = 1000
    #schedule timeout retry period in milliseconds
    timeoutRetryPeriod = 1000
  }
  undo {
    logSaveDays = 7
    #schedule delete expired undo_log in milliseconds
    logDeletePeriod = 86400000
  }
  #unit ms,s,m,h,d represents milliseconds, seconds, minutes, hours, days, default permanent
  maxCommitRetryTimeout = "-1"
  maxRollbackRetryTimeout = "-1"
  rollbackRetryTimeoutUnlockEnable = false
}


## metrics configuration, only used in server side
metrics {
  enabled = false
  registryType = "compact"
  # multi exporters use comma divided
  exporterList = "prometheus"
  exporterPrometheusPort = 9898
}

resoures目录下新建registry.conf 配置如下：

registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  type = "nacos"

  nacos {
    serverAddr = "127.0.0.1:8848"
    namespace = ""
    cluster = "seata"
  }
  eureka {
    serviceUrl = "http://localhost:8761/eureka"
    application = "default"
    weight = "1"
  }
  redis {
    serverAddr = "localhost:6379"
    db = "0"
  }
  zk {
    cluster = "default"
    serverAddr = "127.0.0.1:2181"
    session.timeout = 6000
    connect.timeout = 2000
  }
  consul {
    cluster = "default"
    serverAddr = "127.0.0.1:8500"
  }
  etcd3 {
    cluster = "default"
    serverAddr = "http://localhost:2379"
  }
  sofa {
    serverAddr = "127.0.0.1:9603"
    application = "default"
    region = "DEFAULT_ZONE"
    datacenter = "DefaultDataCenter"
    cluster = "default"
    group = "SEATA_GROUP"
    addressWaitTime = "3000"
  }
  file {
    name = "file.conf"
  }
}

config {
  # file、nacos 、apollo、zk、consul、etcd3
  type = "file"

  nacos {
    serverAddr = "localhost"
    namespace = ""
    group = "SEATA_GROUP"
  }
  consul {
    serverAddr = "127.0.0.1:8500"
  }
  apollo {
    app.id = "seata-server"
    apollo.meta = "http://192.168.1.204:8801"
    namespace = "application"
  }
  zk {
    serverAddr = "127.0.0.1:2181"
    session.timeout = 6000
    connect.timeout = 2000
  }
  etcd3 {
    serverAddr = "http://localhost:2379"
  }
  file {
    name = "file.conf"
  }
}

DataSourceProxyConfig数据源加载

  • SEATA是基于数据源拦截来实现的分布式事务，
    需要排除掉SpringBoot默认自动注入的DataSourceAutoConfigurationBean，自定义配置数据源。

在启动类上添加：@SpringBootApplication(exclude = DataSourceAutoConfiguration.class) ，并添加以下配置类

@Configuration
public class DataSourceProxyConfig {

    @Bean
    @ConfigurationProperties(prefix = "spring.datasource")
    public DataSource druidDataSource(){
        return new DruidDataSource();
    }

    @Bean
    public DataSourceProxy dataSourceProxy(DataSource dataSource) {
        return new DataSourceProxy(dataSource);
    }

    @Bean
    public SqlSessionFactory sqlSessionFactoryBean(DataSourceProxy dataSourceProxy) throws Exception {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSourceProxy);
        sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver()
                .getResources("classpath*:/mapper/*Mapper.xml"));
        sqlSessionFactoryBean.setTransactionFactory(new SpringManagedTransactionFactory());
        return sqlSessionFactoryBean.getObject();
    }

    @Bean
    public GlobalTransactionScanner globalTransactionScanner(){
        return new GlobalTransactionScanner("springcloud-alibaba-consumer", "springcloud-alibaba-comsumer-test");
    }
}

创建业务表和undo-log表

CREATE TABLE IF NOT EXISTS `undo_log`
(
    `id`            BIGINT(20)   NOT NULL AUTO_INCREMENT COMMENT 'increment id',
    `branch_id`     BIGINT(20)   NOT NULL COMMENT 'branch transaction id',
    `xid`           VARCHAR(100) NOT NULL COMMENT 'global transaction id',
    `context`       VARCHAR(128) NOT NULL COMMENT 'undo_log context,such as serialization',
    `rollback_info` LONGBLOB     NOT NULL COMMENT 'rollback info',
    `log_status`    INT(11)      NOT NULL COMMENT '0:normal status,1:defense status',
    `log_created`   DATETIME     NOT NULL COMMENT 'create datetime',
    `log_modified`  DATETIME     NOT NULL COMMENT 'modify datetime',
    PRIMARY KEY (`id`),
    UNIQUE KEY `ux_undo_log` (`xid`, `branch_id`)
) ENGINE = InnoDB
  AUTO_INCREMENT = 1
  DEFAULT CHARSET = utf8 COMMENT ='AT transaction mode undo table';


# 业务数据表
CREATE TABLE `sys_user` (
  `id` varchar(36) NOT NULL,
  `name` varchar(100) NOT NULL,
  `msg` varchar(500) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;


INSERT INTO `sys_user` (`id`, `name`, `msg`) VALUES ('1', '小王', '初始化数据');

核心业务方法

@Override
@GlobalTransactional
public String ceshi(String input) {
    UserPojo userPojo = userPojoMapper.selectByPrimaryKey("1");
    userPojo.setName("luo123");
    userPojoMapper.updateByPrimaryKey(userPojo);
    try {
        // 方便数据库看数据，暂停20秒
        Thread.sleep(20 * 1000);
    } catch (InterruptedException e) {
        e.printStackTrace();
        return "";
    }
    return "Hello World,"+input+"! ,I am "+ userPojo.getName();
}

查看undo_log中的中间临时数据：
在这里插入图片描述
页面调用结果：
在这里插入图片描述

该项目源码：可在我的github中获取

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